Interpretation of JTG 3430-2020 Test methods of soils for highway engineering Standard No.: JTG 3430-2020 Standard name: 公路土工试验规程 English name: Test Methods of Soils for Highway Engineering Issued by: the Ministry of Transport of the People's Republic of China Released on: August 10, 2020 Implementation date: January 1, 2021 Replaced by: JTG E40-2007 Format: PDF Introduction to this standard: This standard was formulated to unify the test methods and determine the engineering properties of soil. This standard applies to determine the engineering properties of foundation soil and filling soil of highway engineering of various grades. A reasonable plan shall be prepared for soil test, representative samples shall be collected, correct data shall be analyzed and collated, and test results in line with the actual situation shall be provided. Test instruments and equipment shall be verified regularly, and the accuracy shall meet the requirements. Test environment shall meet the safety and environment protection requirements. In addition to the requirements stipulated in this standard, the soil test shall also comply with those specified in the current relevant national and professional standards. Recently, the Ministry of Transport has issued JTG 3430-2020 Test Methods of Soils for Highway Engineering (referred to as this standard), which will be implemented from January 1, 2021 as a professional standard of highway engineering. The original JTG E40-2007 Test Methods of Soils for Highway Engineering (hereinafter referred to as the original standard) shall be abolished at the same time. In order to understand the main contents of this revision and implement it well, the relevant revisions are now interpreted as follows: I. Compilation background With a large number of highways in China, especially high-grade highways, extending to the western region, the construction conditions and environment become more complicated. Through a lot of engineering practices, the technical level of highway construction in China has been greatly improved. In terms of scientific research achievements, China has made continuous research on the filling technology of subgrade under various special soils such as saline soil, loess, expansive soil, red clay, high liquid limit soil, frozen soil and complex geological environment, with great achievement. With the development of highway construction, some indexes and test methods in the original standard can no longer meet the needs of engineering. In order to better reflect the technical level of highway construction in China and guide the engineering construction, the Ministry of Transport organized the revision of the original standard. II. Positioning of this standard The revision of this standard summarizes the technical achievements in highway related fields for more than ten years, and implements the development concept of green, safety and environmental protection. In this standard, corresponding test methods and standards for the technical parameters added in the design and construction of highway subgrade are formulated, and some technically outdated test methods are deleted. This standard strives for reasonable test indexes, clear test conditions and strong operability, reflecting the technical level of highway soil test in China, and keeping pace with international advanced standards in general. III Main Contents The main changes in this revision include: (1) Tests added 1) T 0191-2019 Maximum load ratio test The maximum dry density and optimum moisture content of soil reflect the compactness characteristics of soil under different moisture content, while the maximum bearing ratio test reflects the strength characteristics of soil under different moisture content and compaction work. This test provides basis for rational utilization of high liquid limit soil. This index was put forward for the first time in China and incorporated into this standard. 2) T 0194-2019 Dynamic resilience modulus test 3) T 0192-2019 Resilience modulus test of soil in dry-wet cycle 4) T 0193-2019 Resilience modulus test of soil in freeze-thaw cycle JTG D30-2015 Specifications for Design of Highway Subgrades and JTG D50-2017 Specifications for Design of Highway Asphalt Pavement provide the design parameters for dynamic resilience modulus of soil considering environmental effects (wet-dry cycle or freeze-thaw cycle). This revision supplements the dynamic modulus of resilience test of soil under different working conditions, so as to provide accurate and reliable calculation parameters for subgrade and pavement design. 5) T 0195-2019 Salt expansion test of saline soil 6) T 0196-2019 Collapsibility compression test of saline soil As a special kind of soil, saline soil has unique physical and mechanical properties and engineering characteristics. JTG D30-2015 Specifications for design of highway subgrades and Guidelines for highway design and construction in saline soil area stipulate the control indexes of subgrade salt expansion and collapsibility. In this revision, salt expansion and collapsibility tests of saline soil are added to standardize the test methods of saline soil. 7) T 0189-2019 Frost heaving force test of soil Pavement, retaining wall, U-shaped abutment and light abutment in seasonally frozen soil area are often damaged by frost heaving of soil. Measuring the frost heaving force of soil is the premise and basis for rational design of pavement and structure. The frost heaving force test of soil is added in this revision. (2) Tests deleted In this revision, some parallel tests which are basically not used or have poor accuracy are deleted. The test methods deleted are as follows (the test numbers are the same as those of the original standard): 1) T 0105-1993 Proportion method 2) T 0108-1993 Electric soil sampler method 3) T0171-2007 Slaking test 4) T0143-1993 Direct shear test of sandy soil 5) T 0132-1993 “Vibrostand method" for maximum dry density test of coarse-grained soil and giant-grained soil (3) Tests revised The test items in this revision include: 2 Terms and symbols 3 Engineering classification of soil T 0103-2019 Drying method T 0122-2019 Consistency test T 0172-2019 Standard moisture absorption and moisture content test T 0131-2019 Compaction test T 0134-2019 CBR test T 0140-2019 Slow shear test T 0141-2019 Consolidation fast shear test T 0142-2019 Fast shear test (4) Layout format modified Repetitive contents in different test methods, such as the same instrument and the same test steps are not discussed, reducing the space and simplifying the test contents. The contents of each chapter and the text of the explanation of provisions are partially modified and the validity is confirmed. IV. Precautions (1) The user shall have a correct understanding of the method, test conditions and result processing of each test in this standard so as to better apply them to engineering practice. (2) In case of special materials or special conditions, when the provisions of this standard cannot be fully applied, special demonstration and test research shall be carried out, and reliable technical parameters shall be implemented safely to prevent risks. JTG 3430-2020 Test Methods of Soils for Highway Engineering (English Version)